v,w,x,y=map(float,input().split())
print(float((abs(v-x)**2)+abs(w-y)**2)**(1/2)) v,w,x,y=map(float,input().split()) v map(float,input().split()) map float input().split() ().split () input split w x y print(float((abs(v-x)**2)+abs(w-y)**2)**(1/2)) print float((abs(v-x)**2)+abs(w-y)**2)**(1/2) float((abs(v-x)**2)+abs(w-y)**2) float (abs(v-x)**2)+abs(w-y)**2 abs(v-x)**2 abs(v-x) abs v-x v x 2 abs(w-y)**2 abs(w-y) abs w-y w y 2 1/2 1 2 v,w,x,y=map(float,input().split()) map(float,input().split()) v w,x,y=map(float,input().split()) map(float,input().split()) w x,y=map(float,input().split()) map(float,input().split()) x y=map(float,input().split()) map(float,input().split()) y
v,w,x,y=map(float,input().split())
print(float((abs(v-x)**2)+abs(w-y)**2)**(1/2))